1. Technical Field
The present invention relates to an image formation apparatus and an image formation system.
2. Related Art
In the technical field to which the present invention pertains, an image formation apparatus such as a laser beam printer or the like is widely known. In a typical configuration thereof, an image formation apparatus of the related art has a containing section and a developer carrier; in such a typical configuration, the containing section, which has an opening, contains a developer; the developer carrier is exposed at the opening; the developer carrier is configured to carry a developer; and the developer carrier is configured so that it can rotate. Having such a containing section and a developer carrier, an image formation apparatus of the related art is configured so that the developer carrier thereof develops a latent image that is formed on an image carrier by means of a developer that is contained in the containing section.
In addition to the above-described constituent elements, in order to guarantee that the containing section contains a sufficient amount of a developer, the image formation apparatus of the related art further includes a replenishing member that replenishes a developer into the containing section; and a detecting member that detects whether the height of a developer that is contained in the containing section is at a replenishment start level at which replenishment performed by the replenishing member should be started or not and further detects whether the height of a developer that is contained in the containing section is at a replenishment end level at which replenishment performed by the replenishing member should be ended or not. Having such a configuration, for example, the image formation apparatus of the related art starts the replenishment of a developer that is performed by the replenishing member at the time when the detecting member detects that the height of the developer that is contained in the containing section is at the replenishment start level and ends the replenishment of the developer that is performed by the replenishing member at the time when the detecting member detects that the height of the developer that is contained in the containing section is at the replenishment end level. By this means, the image formation apparatus of the related art ensures that a sufficient amount of a developer is contained in the containing section while further ensuring that the amount thereof never becomes excessive.
In the configuration of the image formation apparatus of the related art, the rotation speed of the developer carrier described above is not constant; that is, the rotation speeds of the developer carrier differ from each other depending on predetermined speed modes. The developer carrier rotates on the basis of either a first speed mode or a second speed mode so as to develop a latent image that is formed on an image carrier, where the first speed mode has a faster (i.e., greater) speed of rotation of the developer carrier, and the second speed mode has a slower (i.e., less) speed of rotation of the developer carrier. In the configuration of the image formation apparatus of the related art, regardless of the speed modes, the replenishing member replenishes a developer into the containing section until the detecting member detects that the height of the developer that is contained in the containing section is at the replenishment end level at which the replenishment performed by the replenishing member should be ended. The configuration of the image formation apparatus of the related art is described in Japanese Patent No. 3,681,642 and JP-A-6-59575.
As the developer carrier, which is provided in such a manner that it is partially exposed at the opening, rotates, air enters the containing section via the opening. Depending on the rotation speed of the developer carrier, the amount of air that enters the containing section varies from one to another. Specifically, when the developer carrier rotates in the first speed mode, the amount of air that enters the containing section via the opening because of air entrainment that is attributable to the rotation of the developer carrier is relatively large. On the other hand, when the developer carrier rotates in the second speed mode, the amount of air that enters the containing section via the opening because of air entrainment that is attributable to the rotation of the developer carrier is relatively small.
For this reason, the amount of air that is entrained when the developer carrier rotates in the second speed mode at the time of the replenishing of the developer on the condition that the developer is replenished until the detecting member detects that the height of the developer that is retained in the containing section has reached the replenishment end level is smaller in comparison with the amount of air that is entrained when the developer carrier rotates in the first speed mode at the time of the replenishing of the developer on the same condition as above, that is, on the condition that the developer is replenished until the detecting member detects that the height of the developer that is retained in the containing section has reached the replenishment end level. Accordingly, the amount of air that is contained in the containing section when the developer carrier rotates in the second speed mode at the time of the replenishing of the developer is smaller in comparison with the amount of air that is contained in the containing section when the developer carrier rotates in the first speed mode at the time of the replenishing of the developer. That is, the density of the developer that is contained in the containing section when the developer carrier rotates in the second speed mode at the time of the replenishing of the developer is greater in comparison with the density of the developer that is contained in the containing section when the developer carrier rotates in the first speed mode at the time of the replenishing of the developer. As a result thereof, the amount of the developer that is contained in the containing section when the developer carrier rotates in the second speed mode at the time of the replenishing of the developer is larger in comparison with the amount of the developer that is contained in the containing section when the developer carrier rotates in the first speed mode at the time of the replenishing of the developer.
Then, if the rotation of the developer carrier enters the first speed mode for the purpose of developing a latent image after that the amount of the developer that is contained in the containing section has increased (become relatively large) due to the replenishing of the developer performed when the developer carrier rotates in the second speed mode, air further enters the containing section via the opening because of air entrainment that is attributable to the rotation of the developer carrier with an increased speed, which results in a decrease in the density of the developer. As a result thereof, there is an adverse possibility that the height of the developer that is retained in the containing section could go over the replenishment end level at which the replenishing of the developer should be ended, which could cause the leakage of the developer out of the containing section.